Golf ball with ground down medial layer

ABSTRACT

A golf ball includes a core, one or more inlaid portions formed into the core, and a second layer disposed radially outward of both the core and the one or more inlaid portions. The core and the one or more inlaid portions cooperate to define a continuous spherical surface, and the core and the second layer cooperate to surround each of the one or more inlaid portions. The one or more inlaid portions are formed by over-molding the core, and then removing the over-molded material back to at least the outer surface of the core.

TECHNICAL FIELD

The present invention relates generally to a multi-layer golf ball.

BACKGROUND

The game of golf is an increasingly popular sport at both the amateur and professional levels. To account for the wide variety of play styles and abilities, it is desirable to produce golf balls having different play characteristics.

Attempts have been made to balance a soft feel with good resilience in a multi-layer golf ball by giving the ball a hardness distribution across its respective layers (core, intermediate layer and cover) in such a way as to retain both properties. A harder golf ball will generally achieve greater distances, but a poor feel when hit. On the other hand, a softer ball will generally give a good feel, but will lack distance. Additionally, certain design characteristics may affect the “feel” of the ball when hit, as well as the durability of the ball.

SUMMARY

A golf ball includes a core, one or more inlaid portions formed into the core, and a second layer disposed radially outward of both the core and the one or more inlaid portions.

The core and the one or more inlaid portions cooperate to define a continuous spherical surface, and the core and the second layer cooperate to surround each of the one or more inlaid portions. The one or more inlaid portions define from about 25% to about 70% of the continuous spherical surface. Additionally, the second layer contacts the continuous spherical surface across the entire spherical surface.

In one configuration, the core, the one or more inlaid portions, and the second layer are each formed from a different material. The one or more inlaid portions have a hardness value, measured on the Shore D scale, that is less than the hardness values for both the core and the second layer. In another configuration, the core and the one or more inlaid portions are formed from the same material composition, though having differing hardness values, while the second layer is formed from a different material from the core and the one or more inlaid portions. In such a configuration, the one or more inlaid portions may have a hardness value, measured on the Shore D scale, that is less than the hardness value of the core, or less than the hardness values for both the core and the second layer.

The core includes a plurality of protrusions and one or more recesses. The one or more inlaid portions are disposed within the one or more recesses such that the one or more inlaid portions and the plurality of protrusions cooperate to define the continuous spherical surface. The one or more recesses may be symmetrically disposed about the core. In one configuration, one of the one or more inlaid portions surrounds more than 50 of the plurality of protrusions on the common spherical surface. In one configuration, there are more than 50 of at least one of the plurality of protrusions and the one or more recesses.

The golf ball further includes a cover surrounding the second layer, wherein the cover includes a plurality of dimples formed into a radially outward surface.

One method of making this multi-layer golf ball begins by molding a substantially spherical core from a first material. The core includes a surface that extends to a first, maximal, radial distance and wherein the surface defines a one or more recessed areas that extend to a second, minimal, radial distance.

The core is then over-molded with a second material such that the second material fills the one or more recessed areas and extends radially outward to a third radial distance. This third radial distance is greater than the first radial distance, and the core and the over-molded second material form a first intermediate ball.

Material is then removed from the first intermediate ball to form a second intermediate ball. The second intermediate ball has a continuous spherical surface at a fourth radial distance, wherein the fourth radial distance is less than or equal to the first radial distance and greater than the second radial distance. As such, the first material and the second material cooperate to define the continuous spherical surface. The second intermediate ball is then over-molded with a third material.

The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description when taken in connection with the accompanying drawings.

“A,” “an,” “the,” “at least one,” and “one or more” are used interchangeably to indicate that at least one of the item is present; a plurality of such items may be present unless the context clearly indicates otherwise. All numerical values of parameters (e.g., of quantities or conditions) in this specification, including the appended claims, are to be understood as being modified in all instances by the term “about” whether or not “about” actually appears before the numerical value. “About” indicates that the stated numerical value allows some slight imprecision (with some approach to exactness in the value; about or reasonably close to the value; nearly). If the imprecision provided by “about” is not otherwise understood in the art with this ordinary meaning, then “about” as used herein indicates at least variations that may arise from ordinary methods of measuring and using such parameters. In addition, disclosure of ranges includes disclosure of all values and further divided ranges within the entire range. Each value within a range and the endpoints of a range are hereby all disclosed as separate embodiment. In this description of the invention, for convenience, “polymer” and “resin” are used interchangeably to encompass resins, oligomers, and polymers. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated items, but do not preclude the presence of other items. As used in this specification, the term “or” includes any and all combinations of one or more of the listed items. When the terms first, second, third, etc. are used to differentiate various items from each other, these designations are merely for convenience and do not limit the items.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic, partial cross-sectional view of a multi layered golf ball having a core and a cover.

FIG. 2 is a schematic partial cross-sectional view of a multi layered golf ball having a core, an intermediate layer, and a cover.

FIG. 3A is an isometric view of a first embodiment of a core.

FIG. 3B is an isometric view of the core of 3A including a plurality of inlaid portions disposed about the core.

FIG. 4A is an isometric view of a second embodiment of a core.

FIG. 4B is an isometric view of the core of 4A including a plurality of inlaid portions disposed about the core.

FIG. 5A is an isometric view of a third embodiment of a core.

FIG. 5B is an isometric view of the core of 5A including an inlaid portion disposed about the core.

FIG. 6A is an isometric view of a fourth embodiment of a core.

FIG. 6B is an isometric view of the core of 6A including an inlaid portion disposed about the core.

FIG. 7 is a schematic flow diagram illustrating a method of manufacturing a golf ball having a plurality of inlaid portions formed into the core.

FIG. 8 is a schematic cross-sectional view of an intermediate ball assembly with a material over-molded about a core.

FIG. 9 is a schematic cross-sectional view of the intermediate ball assembly of FIG. 8, with the over-molded material ground down to a smaller radial dimension to form a second intermediate ball assembly.

FIG. 10 is a schematic cross-sectional view of the second intermediate ball assembly of FIG. 9, with an intermediate layer over-molded about the core and one or more inlaid portions.

DETAILED DESCRIPTION

Referring to the drawings, wherein like reference numerals are used to identify like or identical components in the various views, FIG. 1 schematically illustrates a partial cross-sectional view 10 of a multi layered golf ball 12. In all embodiments of the present invention, the golf ball 12 includes at least a core 14, a cover 16, and one or more inlaid portions 18. In some embodiments, such as schematically illustrated in FIG. 2, the golf ball 12 may include one or more intermediate layers 20 between the core 14 and cover 16 (i.e., where the core 14 is the most radially inward portion of the ball 12, the one or more intermediate layers 20 surround the core 14, and the cover 16 surrounds both the core 14 and the one or more intermediate layers 20).

The one or more inlaid portions 18 may be formed into the core 14, such as shown in FIG. 1, into at least one of the one or more intermediate layers 20, such as shown in FIG. 2, or into both the core 14 and at least one of the one or more intermediate layers 20. As used herein, an inlaid portion 18 is “formed into” a given layer if the inlaid portion 20 and the respective layer cooperate to form a continuous spherical surface on the radially outward facing surface of the respective layer. For example, as shown in FIG. 1, the one or more inlaid portions 18 are inlaid into the core 14 such that the inlaid portions 18 and core 14 cooperate to define a first spherical surface 22. In a similar manner, the one or more inlaid portions 18 may be inlaid into the intermediate layer 20 such that the inlaid portions 18 and intermediate layer 20 cooperate to define a second spherical surface.

FIGS. 3B, 4B, 5B, and 6B schematically illustrate four embodiments of the one or more inlaid portions 18 formed into the core 14. It should be noted that these configurations may be equally used with an intermediate layer 20 instead of the core 14. FIGS. 3B and 4B illustrate embodiments 30, 32, where the one or more inlaid portions 18 include a plurality of discrete inlaid portions 18 distributed about the core 14. Conversely, FIGS. 5B and 6B illustrate embodiments 34, 36 where there is only a single inlaid portion 18 that is disposed in a web-like manner about the core 14.

Depending on how they are specifically configured, the one or more inlaid portions 18 may be used to alter the sound response, feel, and/or durability of the golf ball 12. For example, in an embodiment with a plurality of discrete inlaid portions 18, such as the embodiments 30, 32 provided in FIGS. 3B and 4B, the inlaid portions 18 may be formed from a material that is softer than the core 14, and may serve to dampen acoustic vibrations, and/or lower the tonal response frequency of the ball 12. Conversely, if a harder material is used in a web-like inlay, such as the embodiments 34, 36 provided in FIGS. 5B and 6B, the inlay may be operative to elastically compress the core 14 prior to the formation of the remaining portions of the ball 10, which may alter the response and feel of the ball 12.

In addition to altering the impact response of the ball 12, the one or more inlaid portions 18 may be designed to promote adhesion between the adjacent layers. For example, in one configuration, where a first layer is formed from a thermoplastic polymer, and an adjacent layer is formed from a thermosetting polymer, the one or more inlaid portions 18 may be formed from a partially cross-linked thermoplastic material that has an affinity to bond with both the selected thermoplastic polymer of the first layer, and with the selected thermosetting material of the second layer. For example, the one or more inlaid portions 18 may be formed from a partially crosslinked ionomer. In this manner, the one or more inlaid portions 18 may promote the interconnection of the adjacent layers without affecting the performance of the ball 12 to the same degree as if an entire spherical layer was formed from the material. This may promote increased durability in the finished ball (i.e., where “durability” is specifically the avoidance of adjacent layers from separating or becoming delaminated).

In one configuration, the core 14 may be formed from a thermoplastic material including an ionomeric material, a highly neutralized ionomer resin, a polyamide resin, a polyester resin, or a polyurethane resin. In one configuration, the core 14 may be formed from an ionomer, such as one that may have a Vicat softening temperature, measured according to ASTM D1525, of between about 45° C. and about 65° C., or alternatively between about 50 ° C. and about 55° C. Suitable thermoplastic ionomeric materials are commercially available, for example, from the E. I. du Pont de Nemours and Company under the tradename Surlyn®. Alternatively, a highly neutralized ionomer resin may be used, such as those commercially available from E. I. du Pont de Nemours and Company under the tradename HPF1000, HPF2000, or AD1035.

Likewise, in one configuration, the intermediate layer 20 may be formed from a thermosetting material including polyurethane elastomer, polyamide elastomer, polyurea elastomer, diene-containing polymer (such as polybutadiene), crosslinked metallocene catalyzed polyolefin, or silicone. In one configuration, the intermediate layer 20 may be formed from a diene-rubber material, which may include a main rubber (e.g., a polybutadiene), an unsaturated carboxylic acid or metal salt thereof, a metal oxide, and an organic peroxide. As such, the use of ionomeric or ethyele acid copolymer, or polar ethylene copolymer materials to form the one or more inlaid portions 18 may aid in bonding the thermoplastic ionomer core 14 with the rubber-based intermediate layer 20.

FIGS. 3A, 4A, 5A, and 6A schematically illustrate golf ball cores 14 prior to forming the inlaid portions 18. As shown, FIG. 3A schematically illustrates a core 14 that includes a plurality of concave surface recesses 40 that extend radially inward. In such an embodiment, the core may have a surface geometry such as disclosed in U.S. patent application Ser. No. 13/935,977, filed on Jul. 5, 2013 to Ishii et al. and entitled “Multi-layer Golf Ball,” which is hereby incorporated by reference in its entirety. In this configuration, the recesses 40 may be generally circular in nature, however, as schematically illustrated in FIG. 4A, in another configuration, the core 14 may include a plurality of polygonal recesses 42 instead of circular recesses 40.

FIGS. 5A and 6A schematically illustrate embodiments 34, 36 of a core 14 that includes a plurality of polygonal protrusions 44, instead of recesses such as shown in FIGS. 3A and 4A. In such an embodiment, the core may have a surface geometry such as disclosed in U.S. patent application Ser. No. 13/935,953, filed on Jul. 5, 2013 to Ishii et al. and entitled “Multi-layer Golf Ball,” or in U.S. patent application Ser. No. 14/075,339, filed on Nov. 8, 2013 to Ishii et al. and entitled “Multi-layer Golf Ball,” both of which are hereby incorporated by reference in their entirety.

As shown in each of these embodiments, the core 14 may have a plurality of recesses and/or protrusions. In one configuration, there may be, for example, more than 50 of at least one of the protrusions and the recesses. In an embodiment where there are more than 50 protrusions, an inlaid portion 18 may entirely surround at least 50 of the protrusions on the common spherical surface 22. With reference to FIGS. 5B and 6B, this may occur if the inlaid portion 18 has a web-like appearance. In one configuration, the one or more inlaid portions 18 may form from about 25% to about 70% of the total surface area of the spherical surface 22. In another configuration, the one or more inlaid portions 18 may form from about 40% to about 60% of the total surface area of the spherical surface 22.

In a preferable arrangement, the one or more recesses are symmetrically disposed about the core 14. In an embodiment such as shown in FIGS. 3A or 4A, this may entail having the recesses 40, 42 disposed in a manner such that they are symmetrical about each of three orthogonal planes that bisect the core 14. In an embodiment such as shown in FIGS. 5A or 6A, this may entail having the single, web-like recess similarly disposed in a manner such that it is symmetrical about each of three orthogonal planes that bisect the core 14.

While the described embodiments 30, 32, 34, 36 are all varying designs of a core 14, in another configuration, they may equally represent the outer contours of an intermediate layer 20. In either case, the plurality of recesses 40, 42 and/or polygonal protrusions 44 may be formed into the core through any suitable molding process. For example, in one configuration, molding techniques such as injection molding or compression molding may be used to form the surface texture.

FIG. 7 illustrates a schematic method 50 of manufacturing a golf ball 12 with a plurality of inlaid portions 18 formed into the core 14. It should be understood that this process may be readily adapted to provide a plurality of inlaid portions 18 in an intermediate layer 20 As shown, the method 50 begins at 52 with the molding/fabrication of a textured core 14. The core 14 may be formed through, for example, injection molding, compression molding, 3D printing, or any other suitable forming method. The core 14 may be solid, foamed, or with a hollow interior portion. While it is preferred for the surface texture to be formed during the initial molding operation (i.e., for simplicity in manufacturing), it may also be imparted to a spherical core through a secondary machining operation.

Once the core 14 is formed at 52, it may be over-molded at 54 with the material that is intended to form the one or more inlaid portions 18. This over-molding step may occur through, for example, an injection molding or a compression molding process, and may completely encapsulate the core 14. Said another way, this material may entirely surround the core 14 while leaving no interstitial voids. A schematic representation of this intermediate step is provided in FIG. 8, where the over-molded material 70 contacts the core 14 across the entire surface 72 of the core 14. In this manner, the over-molded material 70 fills any recesses that may be provided into the core 14. Through the materials selected for the core 14 and inlaid portions 18 and/or through the use of an adhesive or adhesion promoter, the over-molded material 70 may adhere to the core 14 across the entire surface 72.

Returning to FIG. 7, once the core 14 has been over-molded at 54, the over-molded material 70 may be ground down at 56. During this step, with reference to FIGS. 8 and 9, the maximal radial dimension of the ball 12 with the over-molded material 70 may be ground down from a first radial dimension 74 (shown in FIG. 8) to a second radial dimension 76 (shown in FIG. 9). In one configuration, the second radial dimension 76 may be less than or equal to the maximal radial dimension 78 of the core 14 prior to the grinding operation, but greater than a minimum radial dimension 80. In this manner, the majority of the over-molded material 70 may be removed, however, the material 70 would still be present in the recesses of the core 14, and the inlaid portions 18 and the core 14 would cooperate to define a single spherical surface 22.

FIGS. 3B, 4B, 5B, and 6B schematically illustrate the golf ball cores 14 from FIGS. 3A, 4A, 5A, and 6A (respectively) following the grinding operation of step 56, which is used to expose the inlaid portions 18. As shown, in each embodiment, the over-molded material 70 is reduced to the shape formed by the intersection of the recesses and the spherical surface 22 of the second radial dimension 76.

Referring to FIGS. 8, in one configuration, the difference between the first radial dimension 74 and the maximal radial dimension 78 of the core 14 may be from about 0.1 mm to about 25 mm. In another embodiment, the difference may be from about 1 mm to about 3 mm. This difference may be sized to minimize material waste that may occur through the grinding process, while still providing adequate space for the over-molded material 70 to flow throughout the mold during the over-molding step 54.

Referring again to FIG. 7, following the grinding step at 56, the core 14 with the one or more inlaid portions 18 may be again over-molded at 58 to form a second layer 82 (shown schematically in FIG. 10) that is radially exterior to both the core 14 and the one or more inlaid portions 18. The second layer 82 may be an intermediate layer 20 or a cover 16, depending on the construction of the ball (i.e., a 3 or more layer ball, or a 2 layer ball), and may directly contact both the core 14 and the one or more inlaid portions 18. Said another way, the core 14 and the second layer 82 may cooperate to surround the one or more inlaid portions 18. In a configuration where the inlaid portions 18 are provided in the intermediate layer 20, the second layer 82 may then be a second intermediate layer 20 or a cover 16. This second layer 82 may be molded, for example, through injection molding, compression molding, or through any other suitable molding process known in the art.

In a configuration where the ball is a 4 or more piece ball, remaining intermediate layers may be formed in step 60 (in a 3 piece ball, this step may be omitted), and the cover 16 may be formed in step 62 (in a 2 piece ball, this step may be omitted). As described above, the cover 16 may include a plurality of dimples. The cover 16 may be coated by a single top coat or include two or more layers of coating, where one layer is a primer layer adjacent the cover 16 and other layer(s) is a top coat positioned on the primer layer.

As shown in FIG. 9, in one configuration, the one or more inlaid portions 18 may have a maximal radial thickness of from about 0.1 mm to about 5 mm. In another embodiment, the one or more inlaid portions 18 may have a maximal radial thickness of from about 1 mm to about 3 mm This radial thickness corresponds to the difference between the first radial dimension 74 and the second radial dimension 76, as shown in FIGS. 8 and 9.

In an embodiment where the one or more inlaid portions 18 are used to dampen the sound of the ball, the one or more inlaid portions 18 may have a slab hardness value, measured on the Shore D scale, that is less than the slab hardness value for both the core 14 and the second layer 82. For example, in such an embodiment, the one or more inlaid portions 18 may have a slab hardness value of from about 30 D to about 55 D. In other configurations, the one or more inlaid portions 18 may have a slab hardness value that is about equal to or greater than the slab hardness values of the core 14 and the second layer 82. Such a configuration may promote certain force transfer characteristics and/or increase the pitch of the ball when hit.

While various embodiments have been described, the description is intended to be exemplary, rather than limiting and it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the scope of this disclosure. Accordingly, the disclosure is not to be restricted except in light of the attached claims and their equivalents. Also, various modifications and changes may be made within the scope of the attached claims. 

1. A golf ball comprising: a core; one or more inlaid portions formed into the core, wherein the core and the one or more inlaid portions cooperate to define a continuous spherical surface; a second layer disposed radially outward of both the core and the one or more inlaid portions; wherein the core and the second layer cooperate to surround each of the one or more inlaid portions.
 2. The golf ball of claim 1, wherein the core, the one or more inlaid portions, and the second layer are each formed from a different material.
 3. The golf ball of claim 1, wherein the one or more inlaid portions define from about 25% to about 70% of the continuous spherical surface.
 4. The golf ball of claim 1, wherein the one or more inlaid portions have a hardness value, measured on the Shore D scale, that is less than the hardness value of the core.
 5. The golf ball of claim 1, wherein the core includes a plurality of protrusions and one or more recesses; and wherein the one or more inlaid portions are disposed within the one or more recesses such that the one or more inlaid portions and the plurality of protrusions cooperate to define the continuous spherical surface.
 6. The golf ball of claim 5, wherein the one or more recesses are symmetrically disposed about the core.
 7. The golf ball of claim 5, wherein one of the one or more inlaid portions surrounds more than 50 of the plurality of protrusions on the common spherical surface.
 8. The golf ball of claim 5, wherein there are more than 50 of at least one of the plurality of protrusions and the one or more recesses.
 9. The golf ball of claim 1, wherein the second layer contacts the continuous spherical surface across the entire spherical surface.
 10. The golf ball of claim 1, further comprising a cover surrounding the second layer, wherein the cover includes a plurality of dimples formed into a radially outward surface.
 11. The golf ball of claim 1, wherein the core is formed from a thermoplastic polymer that includes an ionomeric material, a highly neutralized ionomer resin, a polyamide resin, a polyester resin, or a polyurethane resin; wherein the one or more inlaid portions are formed from an ethylene copolymers or an ionomeric material; and wherein the second layer is formed from a thermoset polymer that includes a polyurethane elastomer, a polyamide elastomer, a polyurea elastomer, a diene-containing polymer, a crosslinked metallocene catalyzed polyolefin, or a silicone.
 12. The golf ball of claim 1, wherein the one or more inlaid portions have a hardness value, measured on the Shore D scale, that is greater than the hardness value of the core.
 13. A method of making a multi-layer golf ball having one or more inlaid portions formed into a material layer, the method comprising: molding a substantially spherical core from a first material, wherein the core includes a surface that extends to a first, maximal, radial distance and wherein the surface defines a one or more recessed areas that extend to a second, minimal, radial distance; over-molding the core with a second material such that the second material fills the one or more recessed areas and extends radially outward to a third radial distance that is greater than the first radial distance, wherein the core and the over-molded second material form a first intermediate ball; removing material from the first intermediate ball to form a second intermediate ball; wherein the second intermediate ball has a continuous spherical surface at a fourth radial distance; wherein the first material and the second material cooperate to define the continuous spherical surface; wherein the fourth radial distance is less than or equal to the first radial distance and greater than the second radial distance; and over-molding the second intermediate ball with a third material.
 14. The method of claim 13, wherein removing material from the first intermediate ball occurs through grinding.
 15. The method of claim 13, wherein the second material forms from about 25% to about 70% of the continuous spherical surface.
 16. The method of claim 13, wherein the difference between the first radial distance and the third radial distance is from about 1 mm to about 3 mm.
 17. The method of claim 13, wherein the difference between the second radial distance and the fourth radial distance is from about 1 mm to about 3 mm.
 18. The method of claim 13, wherein the one or more recessed areas are symmetrically disposed about the core.
 19. The method of claim 13, further comprising over-molding the third material with a fourth material to form a cover; and wherein the cover includes a plurality of dimples disposed on a radially outer surface.
 20. The method of claim 13, wherein each of molding a substantially spherical core and over-molding the core with a second material respectively includes injection molding. 